If the client is in the process of resetting the session when it receives
a callback, then returning NFS4ERR_DELAY may cause a deadlock with the
DESTROY_SESSION call.

Basically, if the client returns NFS4ERR_DELAY in response to the
CB_SEQUENCE call, then the server is entitled to believe that the
client is busy because it is already processing that call. In that
case, the server is perfectly entitled to respond with a
NFS4ERR_BACK_CHAN_BUSY to any DESTROY_SESSION call.

Fix this by having the client reply with a NFS4ERR_BADSESSION in
response to the callback if it is resetting the session.

Cc: stable@kernel.org [2.6.38+]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Currently, there is no guarantee that we will call nfs4_cb_take_slot() even
though nfs4_callback_compound() will consistently call
nfs4_cb_free_slot() provided the cb_process_state has set the 'clp' field.
The result is that we can trigger the BUG_ON() upon the next call to
nfs4_cb_take_slot().

This patch fixes the above problem by using the slot id that was taken in
the CB_SEQUENCE operation as a flag for whether or not we need to call
nfs4_cb_free_slot().
It also fixes an atomicity problem: we need to set tbl->highest_used_slotid
atomically with the check for NFS4_SESSION_DRAINING, otherwise we end up
racing with the various tests in nfs4_begin_drain_session().

Cc: stable@kernel.org [2.6.38+]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Layouts should be tracked per nfs_server (aka superblock)
instead of per struct nfs_client, which may have multiple FSIDs associated
with it.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Use recalled range to invalidate particular layout segments in the layout cache.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>

pnfs deviceids are unique per server, per layout type.
struct nfs_client is currently used to distinguish deviceids from
different nfs servers, yet these may clash between different layout
types on the same server.  Therefore, use the layout driver associated
with each deviceid at insertion time to look it up, unhash, or
delete it.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>

Note: This functionlaity is incomplete as all layout segments referring to
the 'to be removed device id' need to be reaped, and all in flight I/O drained.

[use be32 res in nfs4_callback_devicenotify]
[use nfs_client to qualify deviceid for cb_notify_deviceid]
[use global deviceid cache for CB_NOTIFY_DEVICEID]
[refactor device cache _lookup_deviceid]
[refactor device cache _find_get_deviceid]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[Bug in new global-device-cache code]
[layout_driver MUST set free_deviceid_node if using dev-cache]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

The pnfs code was using throughout the lock order i_lock, cl_lock.
This conflicts with the nfs delegation code.  Rework the pnfs code
to avoid taking both locks simultaneously.

Currently the code takes the double lock to add/remove the layout to a
nfs_client list, while atomically checking that the list of lsegs is
empty.  To avoid this, we rely on existing serializations.  When a
layout is initialized with lseg count equal zero, LAYOUTGET's
openstateid serialization is in effect, making it safe to assume it
stays zero unless we change it.  And once a layout's lseg count drops
to zero, it is set as DESTROYED and so will stay at zero.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Always assign the cb_process_state nfs_client pointer so a processing error
in cb_sequence after the nfs_client is found and referenced returns
a non-NULL cb_process_state nfs_client and the matching nfs_put_client in
nfs4_callback_compound dereferences the client.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The information required to find the nfs_client cooresponding to the incoming
back channel request is contained in the NFS layer. Perform minimal checking
in the RPC layer pg_authenticate method, and push more detailed checking into
the NFS layer where the nfs_client can be found.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

While here, update the code a bit.

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>